The macrophage is a key component of the innate arm of immunity and is critical in regulating initial immune response to tumors, infections and in inflammation. The macrophage is also a central player in sustaining immune privilege in the eye. Immunosenescence is characterized by age-related changes in both the innate and adaptive compartments of the immune system. Innate immunity, specifically macrophage function, has received particular attention in the eye as it can modulate developmental and post-developmental angiogenesis. Ocular neovascularization plays a central role in visual impairment and blindness in several disease states of the eye, including age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, and intraocular tumors. The work described in this proposal will help elucidate the mechanisms by which senescence induces a functional drift in macrophages towards a deleterious pro-angiogenic phenotype. Our studies will also test how altering macrophage polarization determines angiogenic fate in the eye. These questions are especially relevant to the importance of macrophages in AMD. These goals will be accomplished by: a) Quantifying age-related changes in IL-10 activated signaling pathways in macrophages that lead to loss of anti-angiogenic function and b) Demonstrating that abnormal processing of cholesterol, a dominant component of drusen, causes old macrophages to become pro- angiogenic.